Field of Invention
This invention relates to a method for probing a MOS transistor, and particularly relates to a method for deriving characteristic values of a MOS transistor.
Description of Related Art
The sum (RSD) of the drain resistance RD and the source resistance RS and the effective carrier mobility μeff are important characteristic values for a MOS transistor. Recently, RSD extraction by using a single device is reported in two papers including Da-Wen Lin et al., IEEE Electron Device Letters, Vol. 28, No. 12, pp. 1132-1134, December 2007, and Da-Wen Lin et al., IEEE Transactions on Electron Devices, Vol. 57, No. 4, April 2010. The μeff value is directly calculated from the extracted RSD value. The single device of MOS transistor is illustrated in FIG. 1, together with the designation of certain parameters thereof that will be used hereafter.
The Vt values at different bias configurations and the empirical factor η (˜3 for PFET and ˜2 for NFET) are only inputs in the RSD equations in the above papers. However, if the values of Vt and η are not accurate, the extracted RSD and the μeff derived therefrom are not accurate either.
This invention gives a self-constant iteration method to find the accurate Vt and η so that determine the accurate RSD and μeff.